Governments produce no tangible goods that would enable them to provision themselves and must force their citizens to support them. This is the purpose of taxation, although a currency issuing government never actually needs its own currency back to enable its spending. It does, however, need those citizens to need the currency.

This is why the IRS must maintain a fear factor among the population. People can barter or use anything physical to represent value in trade, until the tax man shows up demanding the currency that only the government can produce. Taxation has never "funded" our government, but is important in providing a unified denomination of economic activity and controlling inflation.

The value of the US dollar is always set by the fact that it retires one dollar of tax obligation. The value of goods and services the dollar denominates is dependent upon the scarcity of those goods and services, not the number of dollars in the economy. All economics comes back to resources and their allocation and has little to do with money.